Vacuum tube construction



Nov. 21, 1933. c. J. KAYKO VACUUM TUBE CONSTRUCTION Filed Aug. 31, 1929 W0 W W 6 dummy.

Pat ented Nov. 21 1933' UNITED STATES,

i VACUUM TUBE CONSTRUCTION o Charles J. Kayko, Jackson, Mich.,a'ssignor, by

mesne assignments, to The S'parlrs-Withington Company, Jackson, Micln, a corporation of Ohio Application August 31,1929. sem No. 289,820 9 4 Claims. 01. 250-215)- My invention relates to vacuum tubes of the type employing uni-potential cathodes provided with cathode heaters energized current. V I

An object of my inventionis to devise an improved vacuum tube structure for supporting the elements of the tube in proper spaced relation. r

A further object of my invention is to devise an improved structure of the cathode element with its heating unit to reduce the alternating current hum due to theheater energizing circuit.

My'invention is illustrated in the accompanyingdrawing in which: a

Figure 1 is a view in elevation, partly'in section, showing the tube elements mounted upon the stem; l v v Figure 21s a side viewof-Figur'e 1-;

Figure 3 is a sectional viewof Figure 1 taken along the line 3-3; I

Figure 4 is an enlarged sectional view of the cathode cylinderwith its heater unit;

Figure 5 is a sectional along the line 5-5.

by alternating Referring to Figure 1, only the internal structure of the tube is shown; the envelope and its basehaving been omitted for the purpose of bet- V .3, 8, 10a, 10b and 12. These wires are embedded ter showing 1 indicates thestem of the tube which is provided with the usual pinch 1a into which-is embedded two parallel rods 2 and 3. Theupper endsof rods 2 and 3 pass through apertures formed ina strip of mica 4,'which serves to maintain the free ends of theserods in proper spaced relation, and also servesas an insulating support for the grid and cathode elements, as will be seen hereinafter. The mica strip is held against longitudinal displacement along the rods by pinches 2a and 3a formed on rods 2 and 3, respectively. A cylindrical plate element 5 is located between rods 2 and 3 and is supported by rod 3. The wire coil 6 forming the grid element is located within plate element 5, and is supported by a rod 7, one end of which extends through an aperture formed in mica "strip 4, and the other end being welded to an angle rod 8 embedded in pinch 1a.. Each turn of the grid coil is preferably welded to rod 7 at the point of contact.

The uni-potential cathode element is located within the grid coil 6 and comprisesa cylinder 9 of nickel or other suitable metal, the upper end of which is spot welded to a metallic rod 9a passing through an aperture in mica strip 4, and being supported from rod 2 by a cross-rod 9b. The upper flattened end of the cathode cylinder 9 view of Figure 1 taken serves to prevent downward displacement of. the mica strip 4 on'rods 2 and 3. The heater element for the cathode comprises a hair-pin filament v10 'threaded through two parallel holes formed in aquartz rod 11, the heater unit being inserted within the cathodev cylinder 9, and the terminals of the filament being welded to rods. 10a and 10b embedded in the pinch of stem 1. There is sufiicient frictional resistance between the cathode cylinder 9 and the quartz rod 11 to support the heater unit from the cathode cylinder. The ends of the filament serve to maintain the lowerlend of the heater and cathode elements in proper position and-prevent lateral displacement. Rods 2, 3, 8, 10a and 10b are provided with terminal conductors 2b,- 3b, 8a, 100 and 1012, serving as leading-in wires for the cathode, plate, grid and heater elements,v respectively, An insulated rod 12 is also embedded in the pinch of the stem and carries at its free .end a cup 12a containing flashing material"? 1 v In the manufacture of, my tube, I prefer to assemble the structure'iniunit assemblies which i in turn are assembled to complete the entiretube" structure, The w stern assembly is preferably formed by sealing into the pinch of .the stem six wires of equal length,corresponding-to rods 2,=.

in the pinch in' onegoperation and are then cut a wire-coil 6 onto an arbor'of particular configure-Vv tion to give'the coil, the special shape shown in Figure 3, and each turn of the coil is welded to the support rod 7. The rod: 7' may be incor- ,porated in *thearbor andhthe wire 6 wound di rectly over it. l v

The plateileleme'nt 5 is formed from a single sheet of metal as indicated in Figure 3, theends of the sheet forming the element being extended in parallel lips 5d and 5b to embrace rod 3.

The cathode element is formed by rolling a sheet of metal, preferably nickel, into a cylindrical-form having a lap seam and an inside diameter large enough to receive quartz rod 11 (see Figs. 3 and 4). The rod 9a is then inserted into one end of the cylinder which is then flattened against the rod and welded thereto'as by spot welding. The cathode cylinder 9 is next coated with suitable material 20 to increase its electron emission over the portion which lies within the grid element. a

The heater unit is formed by cutting to proper length the quartz rod 11 and threading the hairpin filament 10 through the parallel holes in the rod, leaving sufiicient terminal extensions on the filament for welding to the rods 10a and 10b. The heater unit is next inserted into the open end of the cathode cylinder.

With the unit assemblies formed as indicated above the assembly of the completed tube structure is as follows: The formed plate element is placed in position upon rod 3, and the lips 5a and 5b are welded together and to the rod 3 by spot welding. The grid assembly is placed in position within plate 5, and the lower end of rod '7 is welded to angle rod 8. The mica strip 4 is placed over the rod 9a on the cathode and heater unit assembly, and this assembly is insertedintothegrid coil 6, the rods 2, 3 and 7 being guided into their respective apertures in mica strip 4. The ends of filament 10 are bent at right angles and welded to rods 10a and 10b; The mica strip 4 is pressed against the upper flattened end of cathode cylinder 9, and pinches 2a and 3a are then formedin rods 2 and 3, respectively. With the end of the cathode cylinder 9 held firmlyagainst mica strip 4, the rod'9b is welded'to rod 911 and rod 2 to provide mechanical support for the oathode and heater units. strip 4 serves to. prevent lateral displacement of the upper ends of the cathode and grid elements.

From an inspection of the structure which I have devised, it will be seen that the uni-potential cathode cylinder completely shields the entire electron emitting portions of the heater filament 10 and substantially eliminates any disturbing hum due to alternating current flowing in the u4heater circuit. The lower ends of the filament which are-not covered by the cathode cylinder do not operate at a temperature sufficient to cause substantial electron emission, due to the conduction 01 heat away from thefilament by the rods 4031011 and 10b. Furthermore, the electron emitting area of the cathode cylinder islimited to thatarea contained within the grid element, and the portions of the cylinder extending-beyond the ends-of the grid serve simply 'as shielding mieelements. .By this structure direct electron emistJto a minimum It will alsobe seen that I have sion from the'he'ater filament to the plate element-is avoided,"and the electrostatic influence oimthe heater circuit upon the electron stream between thecathode and'theplate is: reduced devised a structure in which the electrical connection'to theuni-potential cathode is made at a: point symmetrical to the cathode axis and external thereoiz What I.claim is:

1. In a vacuum tube structure,the combination of a stem having a single pinch, two spaced rods embedded in the pinch, an insulatingspacer It. will be seen that mica mounted upon said rods near the free ends, a cathode and a heater therefor positioned between said rods, means including leading-in conductors for said heater for supporting one end of said cathode from said pinch, and means including a metallic conductor passing through an aperture 'in said insulating spacer for supporting the other end of said cathode from one of said rods, said'last mentioned means and rod serving as a leading-in conductor for said cathode.

2. In a vacuum tube structure, an evacuated vessel comprising a press, a plurality of metallic members held in said press, two of said metallic members extending substantially the full length ported by one of said long metallic members, a cylindrical cathode connected axially symmetrically at one end to said other long metallic memher, an insulating spacer mounted upon the free ends'of said long metallic members, a heating element within said cathode and insulated therefrom, saidheating element being connected to and supported by two of said short metallic members, said heatingelement support providing means for preventing lateral'displacement of the free end of said cathode. V

3. In a vacuum tube structure, the combination of a stem having a single press, two spaced rods imbedded in said press, a cathode arranged between said rods, an anode surrounding said cathode and supported by oneof said rods, an insulating spacer mounted upon said rods near their free ends above said anode and cathode, and means for supporting said cathode from and making electrical connection with the other of said rods, said means passing through an aperture in said spacer whereby said cathode is held against lateral displacement. g

4. In a vacuum tube structure, an evacuated vessel comprising a press, a plurality of metallic members held in said press, two of said metallic members extending substantially the full length of said vessel and the remainder terminating a short distance from said press, an insulating spacer mounted upon the free ends of said long metallic members, a cathode, a grid surrounding said cathode supported at one end by one of said, short metallic members and at the other end to said insulating spacer, an anode surrounding said grid: supported by one of said long metallic members, and means for. connecting to and sup-,- porting said cathode from the other long metallic member, said means passing throughan aperture in said spacer whereby said cathode is held against lateral displacement.

CHARLES J. KAYKO. 

